This work is directed toward providing better rehabilitation for people suffering from somatosensory loss and paralysis due to spinal cord injury, head trauma or stroke. The objective of this project is to demonstrate that information obtained from recordings of activity in peripheral nerves can be used for modulating functional electrical stimulation of muscle and for providing a sense of touch and limb position from areas of the body suffering sensory loss due to central nervous system trauma. Advances in electrode design and computer-based instrumentation offer a means to separate signals from individual receptors out of recordings made from intact nerves, providing the potential for an unprecedented degree of precision in designing control systems. The thrust of our work is to develop the methodology and instrumentation to extract sensory receptor activity patterns on line, in real time from recordings of afferent activity made with electrodes implanted in individual fascicles of sensory nerves. The specific aims of the proposed project are to: 1) optimize the design of dual-channel intrafascicular electrodes, and obtain data on their performance relative to single-channel electrodes; 2) develop methodologies for the separation and identification of neural activity from individual receptors present in recordings made with dual-channel electrodes; and 3) show that the system can function on a chronic basis in the presence of electrically evoked muscle activity and in unanesthetized animals. At the end of this period we should have adequate data to predict how many implants would be needed to provide a specified amount of sensory feedback for control of functional electrical stimulation. The long-term goal of this work is to develop a system capable of providing sensory feedback for controlling electrically generated movements of hands and limbs in paralyzed patients, or for controlling stimulation of intact sensory systems to provide proprioceptive and tactile sensations from insensate regions. However, such a system could also be used to control prosthetic limbs, by detecting activity among motor neurons in nerve stumps of amputated appendages, and would be of use in basic research on the encoding and processing of sensory information by the nervous system.